Feed axis diagnostic device and diagnostic method for machine tool

Abstract

A feed axis diagnostic device for a machine tool is provided. The machine tool machines a workpiece while driving a moving body with feed axes along a guide surface of a rolling guide mechanism. The feed axis diagnostic device includes a feed axis diagnostic unit configured to detect an abnormality in the rolling guide mechanism in the machine tool. The feed axis diagnostic unit is configured to acquire a feed speed during non-machining and a load applied to the feed axes at the feed speed. The abnormality is detected based on an approximate function calculated from relationships between a plurality of the feed speeds and a plurality of the loads acquired under a plurality of different feed speed conditions in a predetermined period.

What is claimed is: 
     
       1. A feed axis diagnostic device for a machine tool machining a workpiece while driving a moving body defining a feed axis along a guide surface of a rolling guide mechanism, the feed axis diagnostic device comprising:
 a feed axis diagnostic unit configured to detect an abnormality in the rolling guide mechanism of the machine tool, 
 wherein the feed axis diagnostic unit is configured to repeatedly acquire a plurality of feed speeds and a plurality of loads applied to the moving body in the feed axis at the acquired feed speeds in a non-machining state under a plurality of different feed speed conditions during a predetermined period, and 
 wherein the abnormality is detected based on an approximate function calculated from relationships between the plurality of feed speeds and the plurality of loads acquired under the plurality of different feed speed conditions during the predetermined period. 
 
     
     
       2. The feed axis diagnostic device for the machine tool according to  claim 1 , wherein the feed axis diagnostic unit is configured to obtain the plurality of feed speeds and the plurality of loads when the feed axis of the moving body is determined to be at a constant speed during the non-machining. 
     
     
       3. The feed axis diagnostic device for the machine tool according to  claim 1 , wherein a linear approximation is performed in the approximate function, and when a calculated coefficient of the linear approximation is smaller than a preset threshold value, a poor rotation condition of the rolling guide mechanism is determined. 
     
     
       4. The feed axis diagnostic device for the machine tool according to  claim 3 , wherein the linear approximation is performed in the approximate function, and when the calculated coefficient of the linear approximation is smaller than the preset threshold value, and a calculated constant term is greater than a preset threshold value, the poor rotation condition of the rolling guide mechanism is determined. 
     
     
       5. A feed axis diagnostic method that detects an abnormality of a rolling guide mechanism in a machine tool, the method comprising:
 providing the machine tool having the rolling guide mechanism, wherein the machine tool machines a workpiece while driving a moving body defining a feed axis along a guide surface of the rolling guide mechanism; 
 repeatedly acquiring a plurality of feed speeds and a plurality of loads applied to the moving body at the acquired feed speeds in a non-machining state under a plurality of different feed speed conditions during a predetermined period; and 
 detecting the abnormality based on an approximate function calculated from relationships between the plurality of feed speeds and the plurality of loads acquired under the plurality of different feed speed conditions during the predetermined period.